• International Journal of CAD/CAM
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• v.6 no.1
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• pp.29-40
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• 2006

The paper presents an optimization system which integrates a parametric design tool, 3D diffraction-radiation analysis and hydrodynamic performance assessment based on short and long term wave statistics. Controlled by formal optimization strategies the system is able to design offshore structure hulls with superior seakeeping qualities. The parametric modeling tool enables the designer to specify the geometric characteristics of the design from displacement over principal dimensions down to local shape properties. The computer generates the hull form and passes it on to the hydrodynamic analysis, which computes response amplitude operators (RAOs) for forces and motions. Combining the RAOs with short and long-term wave statistics provides a realistic assessment of the quality of the design. The optimization algorithm changes selected shape parameters in order to minimize forces and motions, thus increasing availability and safety of the system. Constraints ensure that only feasible designs with sufficient stability in operation and survival condition are generated. As an example the optimization study of a semisubmersible is discussed. It illustrates how offshore structures can be optimized for a specific target area of operation.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.4
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• pp.177-184
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• 2010

In this study, geometric modeling techniques and their application to ship modeling and design are presented. Traditionally the hull shape is defined by using curves called the lines and various necessary computations are performed based on the discrete points obtained from the lines. However, some applications find difficulty in using the lines such as seakeeping analysis, which requires the computation of wetted part that is changing dynamically over time. To overcome such a problem and increase accuracy and efficiency in computation, two essential geometric modeling techniques, surface modeling and surface-to-surface intersection, are introduced and their application to ship modeling and analysis including hydrostatic computation, slamming and seakeeping analyses is presented.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.2
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• pp.43-52
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• 1998

Generally, the navigational safety of a ship under various loading conditions is evaluated by a loading manual. However, the loading manual handles only statical factors such as weight and buoyancy of ship without including any wave conditions. Practically ship's safety is much concerned with the occurrences on the rough sea as propeller racing, rolling, deck wetness, vertical acceleration, lateral acceleration, slamming and so on. The purpose of this paper is to present a synthetic and practical evaluation method of navigational safety using the integrated seakeeping performance index(ISPI) under loading conditions of ship in seaways. The method is calculated by means of the ISPI by measuring only vertical acceleration. Judgement of dangerousness is carried out for four lading conditions : homogeneous full loaded, half loaded, heavy ballast loaded, and normal ballast loaded conditions. In developing the practical evaluation system of navigational safety, it is useful to solve the difficulties in measuring factors by sensors. And by applying the evaluation diagrames, navigators are able to avoid dangerousness by keeping away of the danger encountering angle of wave direction which the diagram shows.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.86-94
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• 2011

This paper compares frequency domain and time domain predictions from the ShipMo3D ship motion library with observed motions from model tests and sea trials. ShipMo3D evaluates hull radiation and diffraction forces using the frequency domain Green function for zero forward speed, which is a suitable approach for ships travelling at moderate speed (e.g., Froude numbers up to 0.4). Numerical predictions give generally good agreement with experiments. Frequency domain and linear time domain predictions are almost identical. Evaluation of nonlinear buoyancy and incident wave forces using the instantaneous wetted hull surface gives no improvement in numerical predictions. Consistent prediction of roll motions remains a challenge for seakeeping codes due to the associated viscous effects.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.3
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• pp.247-257
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• 2008

In this paper, a free running system, which is developed recently for a 2m-class ship models, will be introduced. For the remote control of hardware, GUI of software packages was developed using Visual Basic 6.0, and Host PC with Positioning Board manages Servo drive. Then the drive operates propeller and rudder. Its control performance will be shown. Also its adaptability to the resistance, manoeuverability and seakeeping model tests will be considered through the installation on a KTTC standard ship model from MOERI.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.89-94
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• 1997

In the design of high speed fishing vessel, its hull form has to be decided from a view point of resistance and propulsion performance without negelction of seakeeping characteristics. In spite of many efforts, the performance improvement by hull form itself has its limitations, specially for high speed craft. In this paper, the development of performance of resistance and seakeeping improving appendage for high speed planing hull on behalft of the hull form of fishing vessel has been introduced. The developed appendage verified its effectiveness in the full scale test.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.16-16
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• 2017

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.1-10
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• 2019

Nowadays, the study on Floating Offshore Wind Turbines (FOWTs) is being performed globally. Dozens of numerical simulation tools have been developed for designing FOWTs and simulating their performances in combined wave and wind environments. On the other hand, model tests are still required to verify the results obtained from numerical simulation tools. To predict seakeeping performance of the OC3-Hywind platform, a OC3 spar model moored by a 3-leg catenary spread mooring system with a delta connection was built with a 1/128 scale ratio. The model tests were carried out for various sea states, including rotating rotor effect with wind in the Ocean Engineering Wide Tank, University Of Ulsan (UOU). The model test results are compared with the numerical simulations by UOU in-house code and FAST.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1994.04a
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• pp.69-79
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• 1994

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.413-414
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• 2010

For the purpose of technological analysis in the marine accidents and their prevention, IMO have made it obligatory to load VDR which is similar to the black box in aircraft. However, in case of body sinkage, capsizing, stranding and plunging which are almost 10% of marine accidents, it is difficult to take out the necessary data from the VDR in order to analyze the cause of them. Therefore, this paper apply the navigation dangerousness evaluation technology to the VDR to improve its performance. And we suggest that the vertical acceleration which is one of the factors for evaluating seakeeping performance of a ship is to be added in the existing VDR record data recommended by IMQ.